From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miles Fidelman Subject: Re: possibly silly question (raid failover) Date: Tue, 01 Nov 2011 09:05:25 -0400 Message-ID: <4EAFEE95.6070608@meetinghouse.net> References: <4EAF3F78.5060900@meetinghouse.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids David Brown wrote: > > One thing to watch out for when making high-availability systems and > using RAID1 (or RAID10), is that RAID1 only tolerates a single failure > in the worst case. If you have built your disk image spread across > different machines with two-copy RAID1, and a server goes down, then > the rest then becomes vulnerable to a single disk failure (or a single > unrecoverable read error). > > It's a different matter if you are building a 4-way mirror from the > four servers, of course. > Just a nit here: I'm looking at "md RAID10" which behaves quite differently that conventional RAID10. Rather than striping and raiding as separate operations, it does both as a unitary operation - essentially spreading n copies of each block across m disks. Rather clever that way. Hence my thought about a 16-disk md RAID10 array - which offers lots of redundancy. Miles -- In theory, there is no difference between theory and practice. In practice, there is. .... Yogi Berra